Two-stroke engines are generally lighter, simpler, and less expensive than four-stroke or diesel engines. Therefore, many devices utilize two-stroke engines. For example, radio-controlled toys, small outboard boat motors, jet skis, off-road motorcycles, and lawn and garden equipment (e.g., lawn mowers, chain saws, leaf blowers, and weed trimmers) will typically utilize two-stroke engines. Although the above-mentioned advantages led to the widespread use of two-stroke engines, these engines possess disadvantages as well. For instance, in a four-stroke engine, the crankcase is completely separate from the combustion chamber, so the crankcase can be filled with oil to lubricate the engine. On the other hand, a two-stroke engine includes no separate oil chamber. Thus, to lubricate a two-stroke engine, oil must be mixed with a fuel, such as gasoline, that is introduced into a fuel-oil tank of the engine. Without the proper amount of oil in the fuel-oil mixture, a two-stroke engine will quickly seize and malfunction. Consequently, great care must be taken to ensure that the proper ratio of fuel to oil is in the mixture that is introduced into the engine.
In most cases, fuel and oil are maintained in separate containers, and then manually metered into and mixed in a third container. Besides using multiple containers, the mixing process can also be messy and difficult to get a proper ratio of fuel to oil. Such difficulty in mixing the fuel and oil for a two-stroke engine is exacerbated by the fact that many people own more than one device that employs a two-stroke engine. Since each two-stroke engine generally requires its own particular fuel-oil ratio, owners of more than one device using a two-stroke engine must repeat the aforementioned mixing process for each device.
Furthermore, it has been recently discovered that volatile vapors escaping to the atmosphere from a container as the fuel-oil mixture is poured into a tank pose a health, safety, and environmental hazard. Accordingly, containers are now being constructed with various types of pour spouts having an internal vent which allow for venting of vapor between the container and the tank into which fuel is flowing. The internal venting container permits for air displacement between the container and the fuel-oil tank to allow a continuous and smooth flow of the fuel-oil mixture without venting any vapor into the atmosphere.
In co-pending and commonly assigned U.S. patent application Ser. No. 11/753,811, which is incorporated herein by reference, a fuel and oil mixing device is described that holds a quantity of fuel and oil and allows a user to readily select the ratio of fuel to oil in the mixture that exits the device, thus allowing a single device to be used to fill multiple two-stroke engines. The fuel and oil mixing device includes a mixing chamber defining an internal volume, a fuel intake opening, an oil intake opening, and an outlet. Fuel is delivered into the mixing chamber from the fuel reservoir through the fuel intake opening, while oil is delivered into the mixing chamber through the oil intake opening. An oil control valve controls oil flowing into the mixing chamber through the oil intake opening so as to allow the user to dispense a fuel-oil mixture through the outlet of the mixing chamber with a predetermined fuel-to-oil ratio.
Such a construction, however, is not readily adaptable to existing fuel containers. Thus, there remains a need in the art for a fuel and oil mixing device that allows a user to accurately and quickly mix the proper amounts of fuel and oil for multiple devices employing a two-stroke engine, preferably a device that can be used with common fuel containers currently in use.